Multicast DNS implementation (initial)

net/dns/mdns_client_impl.h

+// Copyright (c) 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef NET_DNS_MDNS_CLIENT_IMPL_H_
+#define NET_DNS_MDNS_CLIENT_IMPL_H_
+
+#include <map>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include "base/cancelable_callback.h"
+#include "base/observer_list.h"
+#include "base/task_runner.h"
+#include "base/time/clock.h"
+#include "net/base/io_buffer.h"
+#include "net/base/ip_endpoint.h"
+#include "net/dns/mdns_cache.h"
+#include "net/dns/mdns_client.h"
+#include "net/udp/udp_socket.h"
+
+namespace net {
+
+class MDnsListenerImpl;
+
+// This class represents a connection to the network for multicast DNS clients.
+// It reads data into DNSResponse objects and alerts the delegate that a packet
+// has been received.
+class MDnsConnection {

[szym, 2013/06/02 19:01:23]

Since this is internal to mdns_client_impl, I don't think you need this
interface. Instead, I'd suggest making this class internal to MDnsClientImpl so
that it can call its private methods directly.

[Noam Samuel, 2013/06/03 17:57:55]

This class is mocked in the tests to allow separating the testing of the socket
read loop and networking aspects from the testing of other parts of the mdns
logic.

[szym, 2013/06/03 18:38:30]

Whelp! I didn't notice it. This CL is a bit large.

+ public:
+  class Delegate {
+   public:
+    // Handle an mDNS packet buffered in |response| with a size of |bytes_read|.
+    virtual void HandlePacket(DnsResponse* response, int bytes_read) = 0;
+    virtual ~Delegate() {}
+  };
+
+  // Start the connection. Will begin alerting the delegate of packets.
+  virtual bool Init() = 0;
+
+  // Send a packet on both ipv4 and ipv6.
+  virtual bool Send(IOBuffer* buffer, unsigned size) = 0;
+  virtual ~MDnsConnection() {}
+};
+
+class MDnsConnectionFactory {
+ public:
+  virtual scoped_ptr<MDnsConnection> CreateConnection(
+      MDnsConnection::Delegate* delegate,
+      base::TaskRunner* task_runner) = 0;
+
+  virtual ~MDnsConnectionFactory() {}
+};
+
+class MDnsClientImpl : public MDnsClient {
+ public:
+  // The core object exists while the MDnsClient is listening for MDnsPackets,
+  // and is deleted whenever the number of references for listening reachers
+  // zero. The message loop may hold weak pointers to it in order to ensure
+  // tasks scheduled on it are not delivered after it is destroyed.
+  class Core : public base::SupportsWeakPtr<Core>, MDnsConnection::Delegate {
+   public:
+    Core(MDnsClientImpl* client,
+         MDnsConnectionFactory* connection_factory,
+         base::TaskRunner* task_runner,
+         base::Clock* clock);
+    virtual ~Core();
+
+    // Initialize the core. Returns true on success.
+    bool Init();
+
+    // Send a query with a specific rrtype and name. Returns true on success.
+    bool SendQuery(uint16 rrtype, std::string name);
+
+    // Add/remove a listener to the list of listener. May cause network traffic
+    // if listener is active.
+    void AddListener(MDnsListenerImpl* listener, bool alert_existing_records);
+    void RemoveListener(MDnsListenerImpl* listener);
+
+    // Query the cache for records of a specific type and name.
+    void QueryCache(uint16 rrtype, const std::string& name,
+                    std::vector<const RecordParsed*>* records) const;
+
+    // Parse the response and alert relevant listeners.
+    virtual void HandlePacket(DnsResponse* response, int bytes_read) OVERRIDE;
+
+   private:
+    typedef std::pair<uint16, std::string> ListenerKey;
+    typedef std::map<ListenerKey, ObserverList<MDnsListenerImpl>* >
+    ListenerMap;
+
+    // Alert listeners of an update to the cache.
+    void AlertListeners(MDnsUpdateType update_type,
+                        const ListenerKey& key, const RecordParsed* record);
+
+    // Schedule a cleanup to a specific time, cancelling other cleanups.
+    void ScheduleCleanup(base::Time cleanup);
+
+    // Clean up the cache and schedule a new cleanup.
+    void DoCleanup();
+
+    // Callback for when a record is removed from the cache.
+    void OnRecordRemoved(const RecordParsed* record);
+
+    ListenerMap listeners_;
+
+    MDnsClientImpl* client_;
+    MDnsCache cache_;
+
+    base::CancelableCallback<void()> cleanup_callback_;
+    base::Time scheduled_cleanup_;
+
+    scoped_refptr<base::TaskRunner> task_runner_;
+    base::Clock* clock_;
+    scoped_ptr<MDnsConnection> connection_;
+
+    DISALLOW_COPY_AND_ASSIGN(Core);
+  };
+
+  MDnsClientImpl();
+
+  // Used only for testing. Lets users of this class decouple it from time
+  // dependence and network dependence.
+  MDnsClientImpl(base::Clock* clock, base::TaskRunner* task_runner,
+                 MDnsConnectionFactory* connection_factory);
+  virtual ~MDnsClientImpl();
+
+  // Add delegate for RRType |rrtype| and name |name|.
+  // If |name| is an empty string, listen to all notification of type
+  // |rrtype|.
+  virtual scoped_ptr<MDnsListener> CreateListener(
+      uint16 rrtype,
+      const std::string& name,
+      bool active,
+      bool alert_existing_records,
+      MDnsListener::Delegate* delegate) OVERRIDE;
+
+  // Create a transaction to Query MDNS for a single-value query
+  // (A, AAAA, TXT, and SRV) asynchronously. May defer to cache.
+  virtual scoped_ptr<MDnsTransaction> CreateTransaction(
+      uint16 rrtype,
+      const std::string& name,
+      const MDnsTransaction::ResultCallback& callback) OVERRIDE;
+
+  // Functions for testing only.
+  bool IsListeningForTests();
+
+ private:
+  bool AddListenRef();
+  void SubtractListenRef();
+  void Shutdown();
+
+  scoped_ptr<Core> core_;
+  int listen_refs_;
+
+  // Since we can either own or not own clock, use both a scoped_ptr and a ptr.
+  scoped_ptr<base::Clock> clock_owned_;
+  base::Clock* clock_;
+
+  // Since we can either own or not own the connection_factory, use a scoped_ptr
+  // and a ptr.
+  scoped_ptr<MDnsConnectionFactory> connection_factory_owned_;
+  MDnsConnectionFactory* connection_factory_;
+
+  scoped_refptr<base::TaskRunner> task_runner_;
+
+  DISALLOW_COPY_AND_ASSIGN(MDnsClientImpl);
+};
+
+class MDnsListenerImpl : public MDnsListener,
+                         public base::SupportsWeakPtr<MDnsListenerImpl> {
+ public:
+  MDnsListenerImpl(uint16 rrtype,
+                   const std::string& name,
+                   bool active,
+                   bool alert_existing_records,
+                   MDnsListener::Delegate* delegate,
+                   MDnsClientImpl::Core* core);
+
+  // Destroying the listener stops listening.
+  virtual ~MDnsListenerImpl();
+
+  // Get the host or service name for this query.
+  // Return an empty string for no name.
+  virtual const std::string& GetName() const OVERRIDE;
+
+  // Get the type for this query (SRV, TXT, A, AAA, etc)
+  virtual uint16 GetType() const OVERRIDE;
+
+  virtual bool IsActive() const OVERRIDE;
+
+  // Applies only to listeners with names. Will send out a query for new
+  // information. |force_refresh_cache| will force a refresh of all cached
+  // entities.
+  virtual bool SendQuery(bool force_refresh_cache) OVERRIDE;
+
+  // Applies only to listeners with names. Query mDNS cache synchronously for
+  // either single- or multi- valued records.
+  virtual bool QueryCache(
+      std::vector<const RecordParsed*>* records) const OVERRIDE;
+
+  MDnsListener::Delegate* delegate() { return delegate_; }
+
+  void AlertDelegate(MDnsUpdateType update_type,
+                     const RecordParsed* record_parsed);
+ private:
+  uint16 rrtype_;
+  std::string name_;
+  bool active_;
+  MDnsClientImpl::Core* parent_;
+  MDnsListener::Delegate* delegate_;
+
+    DISALLOW_COPY_AND_ASSIGN(MDnsListenerImpl);
+};
+
+class MDnsTransactionImpl : public MDnsTransaction,
+                            public base::SupportsWeakPtr<MDnsTransactionImpl>,
+                            public MDnsListener::Delegate {
+ public:
+  MDnsTransactionImpl(uint16 rrtype,
+                      const std::string& name,
+                      const MDnsTransaction::ResultCallback& callback,
+                      base::TaskRunner* task_runner);
+  virtual ~MDnsTransactionImpl();
+
+  // Start the transaction. Returns true on success.
+  bool Init(MDnsClientImpl* client,
+            MDnsClientImpl::Core* core);
+
+  // MDnsListener::Delegate implementation
+  virtual void OnRecordUpdate(MDnsUpdateType update,
+                              const RecordParsed* record) OVERRIDE;
+  virtual void OnNsecRecord(const std::string& name, unsigned type) OVERRIDE;
+
+  virtual const std::string& GetName() const OVERRIDE;
+  virtual uint16 GetType() const OVERRIDE;
+
+ private:
+  // Trigger the callback and reset all related variables.
+  void TriggerCallback(MDnsTransactionResult result,
+                       const RecordParsed* record);
+
+  // Internal callback for when a cache record is found.
+  void CacheRecordFound(const RecordParsed* record);
+
+  // Callback for when the transaction times out.
+  void OnTimedOut();
+
+  uint16 rrtype_;
+  std::string name_;
+  MDnsTransaction::ResultCallback callback_;
+
+  bool triggered_;
+  scoped_ptr<MDnsListener> listener_;
+  base::CancelableCallback<void()> timeout_;
+  scoped_refptr<base::TaskRunner> task_runner_;
+
+  DISALLOW_COPY_AND_ASSIGN(MDnsTransactionImpl);
+};
+
+// This implementation of MDnsConnection handles connecting to both IPv4 and
+// IPv6.
+class MDnsConnectionImpl : public base::SupportsWeakPtr<MDnsConnectionImpl>,
+                           public MDnsConnection {
+ public:
+  MDnsConnectionImpl(MDnsConnection::Delegate* delegate,
+                     base::TaskRunner* task_runner);
+  virtual ~MDnsConnectionImpl();
+
+  virtual bool Init() OVERRIDE;
+  virtual bool Send(IOBuffer* buffer, unsigned size) OVERRIDE;
+
+ private:
+  // Bind a socket with a specific address size to a specific multicast group
+  // and port 5353.
+  bool BindSocket(UDPSocket* socket,
+                  int addr_size,
+                  const char* multicast_group);
+
+  // Callback for handling a datagram being recieved on either ipv4 or ipv6.
+  // Responsible for ensuring we request another packet from the network.
+  void OnDatagramReceived(UDPSocket* socket,
+                          DnsResponse* response,
+                          IPEndPoint* recv_addr,
+                          int bytes_read);
+
+  // Request another packet from the network.
+  bool ReceiveNextPacket(UDPSocket* socket,
+                        DnsResponse* response,
+                        IPEndPoint* recv_addr);
+
+  // Callback for when sending a query has finished.
+  void SendDone(int sent);
+
+  // The IPEndPoints for sending/recieving packets on IPv4 and IPv6.
+  IPEndPoint GetIPv4SendEndpoint();
+  IPEndPoint GetIPv6SendEndpoint();
+
+  scoped_ptr<UDPSocket> socket_ipv4_;
+  scoped_ptr<UDPSocket> socket_ipv6_;
+
+  scoped_ptr<DnsResponse> response_ipv4_;
+  scoped_ptr<DnsResponse> response_ipv6_;
+
+  // The address from which the last packet was recieved.
+  IPEndPoint recv_addr_ipv4_;
+  IPEndPoint recv_addr_ipv6_;
+
+  MDnsConnection::Delegate* delegate_;
+
+  scoped_refptr<base::TaskRunner> task_runner_;
+
+  DISALLOW_COPY_AND_ASSIGN(MDnsConnectionImpl);
+};
+
+class MDnsConnectionImplFactory : public MDnsConnectionFactory {
+ public:
+  MDnsConnectionImplFactory();
+  virtual ~MDnsConnectionImplFactory();
+
+  virtual scoped_ptr<MDnsConnection> CreateConnection(
+      MDnsConnection::Delegate* delegate,
+      base::TaskRunner* task_runner) OVERRIDE;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(MDnsConnectionImplFactory);
+};
+
+}
+#endif  // NET_DNS_MDNS_CLIENT_IMPL_H_